A new substance has been discovered that can clone any item or creature on the planet. Called C.A.R.D. technology, any Hunter can carry a simple deck of cards that represent the various weapons available. This new discovery leads to the colonization of Ragol 2 and the birth of a new faction (calling themselves the Arkz) who oppose the government's actions.
You can choose either side, the Arkz or Heroes, which both determines the abilities and cards available to you and the strategy decisions you must make in battle. The Heroes are the stronger of the two at first, with various weapons available to them, while the Arkz can summon creatures to their aid. Gameplay is similar to Magic: The Gathering or Yu-Gi-Oh, using the power and abilities of each card in turn to defeat the enemy.
Episode III can be played both offline and online, with the online system using a ranking system so you can compete against fair opponents.